The present invention relates to a method of imparting hydrophilic characteristics to hydrophobic synthetic substrates, such as polyester fibers.
Many synthetic fibers, while having exceedingly useful properties such as durability, permanent press, etc. still lack some of the physical properties desired in a cotton fabric. One of the most notable properties is the hydrophilicity of a cotton fiber. The present invention takes advantage of the cellulose produced by Acetobacter in that it is possible to produce cellulose on the surface of the polyester fiber, thereby giving to the fiber many of the physical properties similar to the cotton fiber. The advantages of the cellulose-synthetic polymer composite are obvious:
(a) greater hydrophilicity and subsequent greater comfort in wearability; PA1 (b) greater absorbancy which may be a useful property for disposal bandages, dressings, and the like; PA1 (c) a natural biosynthetic reaction has been coupled onto the surface of a synthetic polymer as a substrate; and PA1 (d) the altered surface properties of the cellulose-synthetic polymer composite might be advantageous for dyes or several other agents to the surface.
The gram negative bacterium, Acetobacter xylinum, is known to be capable of synthesizing a ribbon comprised of cellulosic microfibrils. Ribbons are generated at the gas-liquid interface of a standing culture. Intertwining ribbons of cellulose produce a thick membrane known as the pellicle. This pellicle is very hydrophilic and has great wet tensile strength.
The bacterial genus Acetobacter is differentiated from other Pseudomonadaceae by its ability to oxidize significant quantities of acetic acid under neutral and acid conditions. The species A. xylinum is characterized by the production of a thick, leathery cellulosic membrane or pellicle under aerobic conditions and on the surface of liquids containing suitable nutrients. Cells of this bacterium are elipsoidal to rod shaped, 0.6-8, with typical gram-negative walls for structures. The envelope consists of an outer lipopolysaccharide membrane and a plasma membrane with a peptidoglycan layer sandwiched in between. No capsule is present. A. xylinum, as well as other species of Acetobacter, is particularly prone to mutation, as purified strains become mixtures of two or more "species" after laboratory maintenance by serial transfer.
It is thus a primary object of the present invention to provide a means for imparting hydrophilic characteristics to hydrophobic substances.
A further object of the present invention provides for the modification of hydrophilic substances to enhance the hydrophilic properties thereof.